Colorimeter plunger



Patented Mar. 16, 1937 UNITED STATES CLORIMETER PLUNGER Walter W. Graeper, Rochester,` N. Y., assignor to Bausch & Lomb Optical Company, Rochester, N. Y., a corporation of New York Application February 1, 1935, Serial No. 4,531

6 Claims.

The present invention relates to optical instruments and more particularly it has reference to means for atta hing transparent optical elements to mountin One of the objects of this invention is to provide an improved means forsecuring transparent optical elements in mountings. Another object is to provide an improved means for securing transparent optical elements in metallic mount- 10 ings without the use of a cementtious substance.

A further object is to provide an improved means for securing colorimeter plungers in metal mountings. A still further object is to provide an improved colorimeter plunger in which the 15 transparent plunger is secured in a metallic mount by a fusible metal and the mount and metal are plated with a non-corroding metal. These and other objects and advantages reside in certain novel features of construction, ar-

' m rangement and combination of parts as will hereinafter be more fully set forth and pointed out in the appended claims.

Referring to the drawing:

Fig. 1 is a front elevation-oi a colorimeter em- 2l bodying my invention.

Fig. 2 is an enlarged sectional view showing an application of my invention for mounting a colorimeter plunger.

Fig. 3 is an enlarged sectional view showing 3o a modified application of my invention for mounting a colorimeter plunger.

Fig. 4 is a top plan view of a fusible ring used in securing the plunger in its mount.

Fig. 5 is an exploded view of three fusible 35 metal rings for securing the plunger in its mount. My invention is illustrated in the drawing wherein I indicates a colorimeter of a well known type having the two adjustably mounted cups I I, the two fixed plungers I2 and the usual viewing 40 tube I3. The plunger I2, which may be of glass, quartz or any suitable transparent material, is removably secured to the stand of the colorimeter III by means of the threaded portion I4 on the annular member I5. The annular member I has a bore I5 within the threaded portion I4 for snugly receiving the end of the plunger I2, and the bore I6 terminates with an inwardly extending shoulder I1 which forms a seat for the end of the plunger I2. An undercut recess I8 is formed at the other end of the interior of the annular member I5 completely surrounding the plunger I2. h

To secure the plunger I2 in the member I5, several split rings I5 of a fusible metal such as 55 solder, are placed in the recess I8 with the openings 20 staggered as shown in Fig. 5. The` metal of the rings I9 has a melting point so low that the fusing temperature will affect neither the plunger I2 nor ring I5. The plunger I2, member I5 and rings I9 are then heated until the fusible metal melts and, when the metal cools a tight frictional bond is formed between the member I5 and the plunger I2. As the member I5 and bonding material I9 are both of metal, it is easy to cover both with a plating 2| of non-corroding metal such as gold, platinum or rhodium. The resultant plunger assembly can then be used with strong acids without damage either to the member I5 or bonding material I9.

In the modification shown in Fig. 3, the member I5 has the bore I5 within the threaded portion I4 for snugly receiving the plunger I2. The plunger I2 is formed with a groove 22 in its outer surface and a similar groove 23 is formed in the undercut recess I8 in the member I5. When the fusible metal rings I9 are placed in the recess I8 and melted, the metal flows into the `grooves 22 and 23 thus forming a tight joint. In this modication, the seating shoulder II for the end of the plunger I2 can be omitted and the threaded portion I4 cut oif in the plane of the end of the plunger I2 as shown. This makes it very easy to clean the end of the plunger. As in the previous form, the member I5 and bonding metal I9 are given a plating 2I of non-corroding metal.

Obviously the plating 2| of non-corroding metal could be eliminated and a non-metallic bonding agent could be used in place of the metallic rings I9. The plating 2|, however, serves'not only to protect the member I5 and the bonding material, but also improves the appearance of the article. The plunger illustrated is of cylindrical form and the outer surface being somewhat rough, there is no need of grooves to create the necessary resistance to movement. My invention is not limited to this shape or condition of the plunger and if the sides of the plunger are polished or if greater resistance to movement is desired, the grooves may be necessary.

From the foregoing it is apparent that I am able to attain the objects of my invention and provide a new and improved means for securing transparent optical elements in metallic mountings and for rendering said mountings non-corrosive. Various modiiications can, of course, be a made without departing from the spirit of my I invention or the scope ofv the appended claims.

I claim:

i. A colorimeter plunger assembly comprising a transparent optical element, an annular member adapted to fit snugly over one end of said element, an internal flange at one end of said member to form a seat for said element, said member being formed with an internal recess at its other end and fusible material in said recess for retaining said element in said member.

2. A colorimeter plunger assembly comprising a transparent plunger having a groove formed in its outer surface, an annular member adapted to t over said rod, said member having a groove on its inner surface and a fusible connecting medium having a melting point lower than that of said member and said plunger extending into both grooves.

3. An article of the character described comprising a transparent plunger having a groove in its outer surface, a member adapted to nt snugly over said plunger, a recessed portion in said member opposite said groove, a groove in said recessed portion and a fusible material filling said recess and said grooves, said plunger and said member terminating in a single plane.

4. A colorimeter plunger assembly comprising a transparent plunger. an annular metallic member having an internal shoulder adapted to form a seat for said plungensaid member having ari internal recess spaced from said shoulder, a fusible metal in said recess for holding said plunger in said member and a layer of non-corroding metal covering the exposed surface of said member and said metal.

5. A colorimeter plunger assembly comprising a transparent plunger having plane, parallel ends. a member adapted to :llt snugly over said plunger. one end of said member being in the plane of one end of said plunger, an internal recess extending around said member at its other end, a metallic bonding element illling said recess and securing said plunger to said member and a layer of noncorroding metal covering the exposed surface of said member and said element.

6. A colorimeter plunger assembly comprising a transparent plunger member, an annular metallic member having a central opening for snugly receiving the end of said plunger member, said opening being enlarged toward the other end of said plunger, a fusible metal of the type which expands upon freezing filling the enlarged portion of said opening, and a non-corroding metal covering said metallic member and said metal.

WALTER W. GRAEPER. 

